1. Field of the Invention
This invention relates in general to the field of security devices and in particular to the field of portable security devices which may be utilized over a wide geographic area. Still more particularly, the present invention relates to portable security devices which may be utilized in conjunction with an emergency transmitter to indicate the location of an emergency situation within a wide geographic area.
2. Description of the Prior Art
Personal security devices are well known in the prior art. Such devices include chemical devices, such as Mace sprays, or acoustic devices, such as sirens or horns. More recently, the field of security devices has expanded to include small hand-held portable transmitters which utilize infrared or radio frequency transmissions to arm or release a security device or lock system.
One example of such a security system is disclosed in U.S. Pat. No. 4,740,775, issued Reese Price on Apr. 26, 1988. This patent discloses an automobile burglar alarm and theft prevention device which includes an alarm circuit including a battery and alarm and vibration detectors which are adapted to close the alarm circuit upon sensing vibrations caused by automobile tampering. The alarm system is armed by the reception of signals generated by a pulse generator which is part of a radio receiving unit within the alarm system which responds to high frequency waves from a push button transmitter.
An additional utilization of a portable transmitter in an alarm system is disclosed in U.S. Pat. No. 4,523,178, issued to George E. Fulhorst on June 11, 1985. In this patent the security system disclosed utilizes a portable transmitter in conjunction with a receiver located within the system operator's vehicle. In the event of an emergency condition, the activation of the portable transmitter and subsequent transmission of a coded signal to the receiver will result in various automobile devices operating, such as horns or lights, to indicate an alarm condition.
Similarly, a system has been recently advertised which includes a small low power portable transmitter which is designed to be carried by the aged or infirm while located within a home or apartment. A receiver tuned to the signals transmitted by the transmitter is coupled to the telephone system and is programmed to dial a predetermined telephone number in response to activation of the transmitter. Thus, an elderly or infirm individual who has an emergency condition which prevents that person from reaching the telephone can, by activation of the portable transmitter, cause an emergency telephone call to be placed to a predetermined telephone number, so that assistance can be rendered by the persons at that location.
However, none of the aforementioned systems disclose a method whereby an individual located within a large geographic area, such as a campus, shopping mall, or athletic stadium, can immediately and accurately summon emergency assistance to a readily determined geographic area. Thus, it should be apparent that a need exists for a system whereby individuals within such a geographic location can simply and easily summon emergency assistance to a precise geographic location within the specified area.